Abstract: This diesel engine (10) has an engine body (11), an EGR device (12), and a control unit (13). The engine body (11) has combustion chambers (15) and injectors (16). The EGR device (12) is provided with: a gas flow path (35) that returns a portion of exhaust gas from the combustion chambers (15) to an intake flow path (17); and an EGR device (37) that has a butterfly valve (42). When the butterfly valve (42) is set to a rotation angle position of 0° when in a closed posture (42A), the control unit (13) drives the butterfly valve (42) within a first rotation angle range of no less than 0° when the injection amount of fuel to be injected by the injectors (16) is no less than a predetermined threshold, and the control unit (13) drives the butterfly valve (42) within a second rotation angle range that passes through 0° when the injection amount is less than the threshold. The threshold is a value greater than zero.